Bitcoin was supposed to be a completely anonymous cryptocurrency. Each transaction would be identified only by public/private keys, and no names and addresses would ever be used. However, it turns out that with a little bit of detective work it isn’t too difficult to identify Bitcoin users in most cases. So if you really, really want to be anonymous, is there any way of doing it?

One option that has recently become available for this purpose is Zcash. Like Bitcoin, Zcash transactions are published on a public blockchain, but users are able to use an optional privacy feature to conceal the sender, recipient, and the amount being transacted. Naturally, this leaves Zcash open to the accusation that it was developed for cyber-crime purposes, so that transactions can be made without any possibility of them being traced by law-enforcement agencies. While this is quite true, there can be quite legitimate reasons for not wanting anyone to trace your financial transactions, which can be summed up as ‘mind your own business’.

In the quaint pre-digital world, when people used to make transactions using dollar bills or gold coins, it was assumed as a foundational principle that a transaction would always be anonymous unless one of the parties decided to make it public. However, if you involved a third party, such as a bank or a credit card company, then things got a bit leakier, because the third party knew a great deal about you and could always provide that information to someone else. Bitcoin was supposed to make things anonymous again, but didn’t. Zcash seems to have taken us back to anonymity again.

Zcash works by a mathematical construct called a zk-SNARK, which sounds like something out of Lewis Carroll’s Alice Through the Looking-Glass, but which I am assured means Zero-Knowledge Succinct Non-Interactive Argument of Knowledge. Please don’t ask me how it works, but you can look it up for yourself if you are so inclined. For those occasions on which you need to have the transaction public (such as having the tax authorities breathing down your neck), you can choose to have either the sender made public, the recipient made public, or both.

Zcash seems to be doing quite well financially for a new(ish) cryptocurrency (its original release date was October 2016). As of the time of writing it has a market cap of just under a billion dollars and is sixteenth out of 1320 currencies in this respect. Undoubtedly it will be heavily used by the cyber-crime world, but I suspect it will be used more and more by people and organizations who have legitimate reasons for wanting their financial transactions to be anonymous. I’ll keep an eye on Zcash from time to time.